The Language Construction Kit
This set of webpages (what's a set of webpages? a webchapter?) is intended for anyone who wants to create artificial languages-- for a fantasy or an alien world, as a hobby, as an interlanguage. It presents linguistically sound methods for creating naturalistic languages-- which can be reversed to create non-naturalistic languages. It suggests further reading for those who want to know more, and shortcuts for those who want to know less.
Well, while not a programming language construction it is still language construction. I remember that this topic also discussed here.
BTW, it is my first try of post here so please excuse me for possible mistakes or misetiquettes.